Non interactive and silent Scheduled tasks

I have some scheduled tasks working with powershell scripts in customer environments.
The powershell script invoke php scripts to execute some tasks in an unattended approach.
Although I have given in the parameters fields the -NonInteractive switch when the scheduled tasks runs the user always sees a small empty command line window (cmd style) screen. Is there any thing it can be done to put the scheduled task running in a silent mode?
Kind regards
LC